It is proposed to investigate the molecular mechanisms involved in the hormonal induction and regulation of fatty acid synthetase and acyl-CoA desaturase in chick embryo liver and cultured liver explants and cells. The rates of synthesis and degradation of the synthetase in insulin, insulin plus thyroxine and hydrocortisone induced liver preparations will be related to the amount of enzyme in these preparations by immunochemical methods. The role of the glycolytic pathway intermediates in the induction of the enzyme will be evaluated by measuring the intracellular levels of these intermediates under conditions where the enzyme is induced. Since the half life of the synthetase in embryo liver after hormonal induction is very much shorter than in adult chicken, we plan to use this system for studies on the properties and mechanisms of turnover of the synthetase. The requirements of different components in the culture medium for the induction of synthetase and Delta 9 and Delta 6 desaturases in cultured liver explants and cells will be evaluated. Antibodies to the purified cyanide sensitive factor will be used to quantitate the amount of CSF protein in newly hatched chicks with different nutritional states and in induced liver explants and cultures.